multi-threading

[LukeOeding]

Hi all, I'm a fan of a lot of the features in HC.jl, but one thing I can't understand is why we only work on a single core instaed of utilizing multiple cores. So I just tried to launch a Julia instance with multiple threads
julia --threads =7,1
but when I got to my solve command I got an error about thread switching (see below). Is there any work in progress about allowing path tracking on multiple cores?

Error:
fatal: error thrown and no exception handler available. ErrorException("cannot switch to task running on another thread") ijl_error at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/rtutils.c:41 ijl_switch at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:639 try_yieldto at ./task.jl:948 wait at ./task.jl:1022 task_done_hook at ./task.jl:694 jfptr_task_done_hook_66740.1 at /Users/lao0004/.julia/juliaup/julia-1.11.5+0.x64.apple.darwin14/lib/julia/sys.dylib (unknown line) jl_apply at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/./julia.h:2157 [inlined] jl_finish_task at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:319 start_task at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:1213 cannot switch to task running on another thread atexit hook threw an error: ErrorException("cannot switch to task running on another thread") ijl_error at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/rtutils.c:41 ijl_switch at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:639 try_yieldto at ./task.jl:948 wait at ./task.jl:1022 uv_write at ./stream.jl:1081 unsafe_write at ./stream.jl:1154 write at ./strings/io.jl:248 [inlined] print at ./strings/io.jl:250 unknown function (ip: 0x17b4fa44d) showerror at ./errorshow.jl:152 unknown function (ip: 0x17bf0f3ed) _atexit at ./initdefs.jl:462 jfptr__atexit_69742.1 at /Users/lao0004/.julia/juliaup/julia-1.11.5+0.x64.apple.darwin14/lib/julia/sys.dylib (unknown line) jl_apply at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/./julia.h:2157 [inlined] ijl_atexit_hook at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/init.c:271 ijl_exit at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/init.c:207 ijl_no_exc_handler at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:698 jl_finish_task at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:322 start_task at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-grannysmith-C07ZQ07RJYVY.0/build/default-grannysmith-C07ZQ07RJYVY-0/julialang/julia-release-1-dot-11/src/task.c:1213

[PBrdng]

Hi, a simple threading mechanism is in fact implemented. See the documentation of solve.

I don't understand your error message. Nevertheless, there are some problems with Julia's threading features and some specific CPU architectures. Can you try to run Julia via julia -t 7,1 and see if that works (see also the documentation)?

[LukeOeding]

Thanks for the reply. I did try the threading = true flag for solve after launching julia with julia -t 7,1 and got the same error ...
fatal: error thrown and no exception handler available.
ErrorException("cannot switch to task running on another thread")

[PBrdng]

I can reproduce this bug. Which is weird, because previously there were no problems (moreover, no tests failed). I will look into it asap.

[PBrdng]

@LukeOeding When I start Julia as julia -t 8 everything runs smoothly. It seems the ,1 option is causing the trouble. Can you verify?

[LukeOeding]

Removing the ,1 option did the trick! Now solve command with threading=true is using 800% of CPU!

[PBrdng]

Great. I will submit an update to the documentation.

[LukeOeding]

The important thing for folks like me who are using VS Code is to modify the julia extension settings to "julia.NumThreads": "auto", which is discussed here. https://discourse.julialang.org/t/multi-threading-not-possible/89698/2